Three out of four top high street stores have begun sales, luring Christmas shoppers with discounts averaging 45%, on the biggest shopping weekend of the year.

Unseasonally warm weather has combined with a lull in shopping in the wake of the Black Friday discount day in late November to create a tense finish to the year’s most important retail period.

Only a few years ago pre-Christmas sales were unusual, as retailers attempted to shift their products at the highest profit margins in the weeks before Christmas, with major discounting only starting on Boxing Day.

But that pattern changed after of the 2008 financial crisis, when shoppers were reluctant to spend and retailers were forced to cut prices early. Since then shoppers and retailers have engaged in an annual competition to see who will blink first, and this year shoppers have once again held back, forcing many retailers into heavy discounting.

Widespread price cuts have occurred as a survey indicated a 5% decline in sales at mid-sized fashion stores last week. The survey, by accountants BDO, covered 40 high street names, including French Connection, Oasis, Hobbs and Karen Millen. “We believe that consumers have become conditioned towards waiting for promotions before making purchases,” BDO wrote.

Mark Hudson, a retail expert at accountancy company PwC said its weekly survey of the top 100 high street retailers found 75% are on sale this week, up from 72% last year, with average discounts of 45% – the same level as last year.

However, Hudson, said there are more cuts to come: “Expect to see further sale activity in the final three days as savvy last-minute shoppers hold out for pre-Christmas bargains.”

On Oxford Street, in London’s West End, on Friday , piles of unsold knitwear and coats were on offer at knock-down prices in nearly every store.

Marks & Spencer is offering 30% off almost all its knitwear, the chain’s most important winter product category, in an apparent panic move as the sale was not backed up by any advertising or online deals. Those knitwear discounts were on top of a widely advertised 30% discount on adult coats. and speculation that the store chain has seen a decline in the number of shoppers in its stores while its online sales are suffering because of problems at the company’s new high-tech warehouse.

Gap, often one of the first chains to go for sales, is offering up to 60% off a vast range of clothing with a further 20% reduction on some items. In its Oxford Circus store in London, H&M had a whole floor of sale items on offer at up to 60% off. Debenhams, Benetton, Miss Selfridge, BHS, Moss Bros, French Connection, Mango and House of Fraser are all offering up to 50%.

Some chains, including Hobbs and French Connection appeared to have about half their stock in the sale, while discounts at Primark and River Island are very limited. Only a few retailers – notably Ted Baker, Next and Mint Velvet – are holding their nerve and sticking to their full prices.

John Lewis, which analysts said was one of the busiest stores on the high street, is only discounting branded items where it is forced to match prices against other retailers as part of its “never knowingly undersold” price promise.

Analysts said the big discounts did not necessarily mean slumping profits. They believe most retailers have limited the damage to their bottom line by being more cautious about the amount of stock ordered this year, so less stock has to be marked down and the sales after Christmas could end early.

Veteran retail analyst Tony Shiret at BESI said: “Its difficult but not desperate. The big guys have been more disciplined than last year.”

Alastair Davies, a retail expert at broker Investec agreed that retailers appeared to have planned more carefully but he said it was too early to tell how their profits might be affected. “Its a nailbiting finish for the clothing sector this year and the sector has a habit of shooting itself in the foot.”